NASA assessing space shuttle foam flaw

By Irene Klotz

CAPE CANAVERAL, Florida (Reuters) – NASA may delay the
launch of space shuttle Discovery on a mission critical to the
spacecraft’s future because of a small crack in the foam
insulation on the ship’s fuel tank, officials said on Monday.

The tank’s insulation has bedeviled NASA since fallen foam
caused the shuttle Columbia to break up, killing seven
astronauts in 2003. Discovery’s flight, which remained targeted
for a 2:38 p.m. EDT launch Tuesday, is intended to prove the
tank, which has been redesigned twice since the accident, no
longer sheds hazardous chunks of foam during launch.

If it fails or if the shuttle sustains some other serious
problem, the shuttle fleet could be grounded permanently,
leaving the future of the half-built International Space
Station in jeopardy.

NASA’s top safety officer and chief engineer had argued for
additional repairs on the tank’s foam before Discovery’s
planned 12-day mission. The new crack was found even before the
shuttle lifted off.

NASA made two attempts to launch Discovery during the
weekend but they were scuttled by poor weather.

Both times, the shuttle’s tank was filled with supercold
propellants and apparently the contraction and expansion in the
liquid oxygen in the tank caused ice to form in the foam
covering a metal bracket.

After the fuel was removed following the decision to
postpone launch, the ice melted, causing the foam to crack.
Inspectors using cameras and sensors found the 5-inch-long,
1/2-inch-wide crack Monday morning, as well as a small foam
wedge that apparently fell from the damaged area and landed on
the launch platform.

CRACK UNDER SCRUTINY

Engineers scrambled to determine how the crack would impact
the mission. The foam that fell is less than half the size of
what would damage the shuttle’s heat shield, had it flown off
during launch instead of on the ground.

NASA wants to ensure the crack will not cause a larger
piece of insulation to fly off.

“Right now we have a good shot at launching tomorrow if we
can clear this particular issue,” launch director Mike Leinbach
said.

Another option is to delay launch until Wednesday to allow
time for workers to inspect the damage close-up.

Discovery’s flight is just the second since the Columbia
disaster. NASA had hoped to resume regular shuttle missions
last year but the foam problem that downed Columbia reoccurred
during Discovery’s launch in July 2005.

A major problem with Discovery on this mission could bring
a premature end to the U.S. space shuttle program and leave the
$100 billion space station, a multi-nation project, unfinished.

NASA has spent $1.3 billion in the past three years to
attempt to fix the foam problem and to make safety upgrades to
the shuttle, which is scheduled for retirement in 2010. Foam
still is still expected to fall off during launch.

The mission is going ahead over objections of senior NASA
safety and technical officers, who wanted more time to work on
the fuel tank’s long-standing foam-shedding problem. But the
space agency says the crew is not at risk because of a plan to
have them stay aboard the space station and await rescue if
their ship was too damaged to safely return home.

(Additional reporting by Jim Loney and Deborah Zabarenko)